The term "chordal speed variation" has long been used to define certain velocity fluctuations observed when a chain is being driven between a pair of sprocket members. Such velocity fluctuations produce spatial positioning errors which are further recognized to depend upon the number of teeth in the drive sprocket and which can be partly reduced by using an odd number of drive teeth. Chain drives are also known for use on various types of "in-line" manufacturing equipment and where parts can be assembled together while both traveling in the same direction. Understandably, the recognized velocity fluctuations promote misalignment and lack of registration between parts being assembled together in this manner and which is especially undesirable for the higher manufacturing speeds constantly being sought.
Roller chain drives wherein the rollers are guided in a pair of straight track sections that extend between the drive and driven sprockets in order to maintain an equal spacing over both chain spans provides still another known means to reduce undesired physical displacement of the chain and any members fixed thereto during its travel between the sprocket members. Such roller chain drives do not avoid the aforementioned velocity fluctuations, however, since the travel speed of the chain link on the straight track is not equal to its travel speed on the drive sprocket. Accordingly, it would be further desirable to modify such fixed track chain drives in a manner retaining the performance advantages achieved with such drive systems while reducing the speed or velocity fluctuations between the fixed track and sprocket components in said drive systems. It would be still further desirable to do so in a manner not requiring either a major structural redesign of the existing fixed track chain drive systems or which produces any accompanying operational impairment.